Generalized Quasi-Walsh PN Sequences and Their Applications in Robust CDMA Communication Systems

Systems of Generalized Quasi-Walsh functions are developed which simultaneously enable multiple access as well as secure communication and jamming resistance. These functions are defined in terms of elementary matrix operations performed on both Sylvester-type and non-Sylvester-type Hadamard matrices. They are employed in orthogonal direct sequence spreading for CDMA communication systems, and allow more users than "pure Walsh encoded" systems allow for this purpose. Zero mutual interference results when a single family of Generalized Quasi-Walsh functions is used in this application. For anti interception and jamming, a pseudo random sequence of isometries post multiply a Hadamard matrix thereby generating the orthogonal direct spreading sequences. Minimal mutual interference is a consequence of the resulting orthogonal spreading. Utilizing bit-by-bit distinct orthogonal codes gives the added benefit of high signal hiding capability and jamming resistance.